Rock drill



June 25, 1929. HARDSQCG 1,718,462

ROCK DRILL Original Filed July 2, 1923 I I @512) ll E I I/IA ;I;// 1 1' i #424 Patented June 25, 1929.

mam mnsoce, or OTTUMWA, Iowa.

nocx mmm.

Application filed July 2, 1923, Serial No.

This invention relates to rock drills and has more specific reference to an improvement in the bit construction and arrangement, particularly in drills of relatlvely large slze.

The objects of this invention are, for the most part, the same as those set forth in my co-pending application filed July' 2, 1923, and bearing Serial No. 648,889, this invention being directed to an fiPPllCtttlOlT of the principles of construction dlsclosed in said co-pending application to relatively large diameter drills.

Other objects and advantages of the 1nvention will be apparent as 1t is better understoodfrom the following descrlption, which, taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

Referring to the drawings,

Figure 1 is a side elevation of a rock d r1ll embodying my invention, the same being shown in operative position 1n a' dull hole;

Fig. 2 is an enlarged vertical sectlon ofthe lower part of the drill bar and the blade carrying socket member;

Fig. 3 is .a horizontal section taken substantially on the line 3-3 n Fig. 2; and

Fig. 4 is a bottom plan VIEW,

As thus illustrated, the dr ll comprlses an elongated bar 21 secured at its upper end in a holding. member 22, which is positloned in the casing of a pneumatic hammer 23, said drill bar carrying at its lower end a bit socket member ,24 in which are positioned a plurality of bits 25, these, in the present. instance, being four in number and arranged at an angle of 90 with respect to each other. Compressed air is supplied through a feed tube 26 to operate a pneumatic hammer. Inasmuch as the details of said hammer are, for the .most part, immaterial, from the standpoint of the invention, they have not been illustrated, it being merely noted that the air is controlled by suitable valve mechanism 27 and serves to operate the hammer, as well as to blow the cuttings from the bottom of the drill hole. A handle 28 is provided for lifting the drill and holding it in operative position. Suitable spring-held guards 29 arepositioned upon the sides of the hammer to prevent the holdin member 21 and bar 22 from dropping out o the ham mer structure when lifted out of the well.

Said drill bar is provided with a central aperture 31 through which the air is directed 848,879. Renewed November 17,1988.

and a similar aperture 32 is provided in the bit carrying member 24. Said member is formed with a shank 33 engaging in a socket The bits 25 are provided with cutting edges 36 and 37 at the bottom and side respectively and are formed with enlarged portions 38 adapted to tightl engage in vertlcal recesses 39 formedili t e lower end of the member 24. vTherecesses 39 are of such form as to prevent lateral withdrawal of the 'blades, which latter -'ma be removed by being knocked out from the top.

Said blades are beveled at their inner bottom edges, as indicated at 41, and contact 1n such manner as to practically form contmuations one of the other.

Eccentric apertures 42 are provided leadng from the central aperture 32 to the bottom of the drill and open between the blades 25. By'this construction, the air passages are free from obstruction and are unlikely to be obstructed by the blades or the cutprovided for rotating the drill during operat1on so that the blades, as arranged, may form a substantiall roul ld hole.

A sleeve, 01 bu et member, 43 is positings. It will be understood that means are tioned about the lower part of the drill bar and has its lower edge su ported upon a shoulder 44 formed in the holdin member 24, this being for the purpose 0 catching and removing cuttingswhich fall back into the hole.

It is thought that the invention and many of 1ts attendant advantages will be understood fromthe foregoing description, and

it will be apparent that various changes may be made in the 'form, construction and M rangement of the parts .without departing from the spirit and scope of the invention, or sacrlficing all of its material advantages,

the form hereinbefore described beingmerely a preferred embodiment thereof.

I claim:

l A rock drill, comprising a drill bar, and a plurality of removable cutter bits arranged at the lower end of mid bar, said bits being formed with a horizontal cutting edge at the bottom and a vertical cutting edge at the side and havin tically extending portions mwardl said cutting edges adapted to be within corresponding recesses in a lower from enlarged versposed .said cutting edges adapted to be part of said drill bar to hold the bits in lace and the bottom cutting edges of sa1d its conver in in matching relation.

2. A rocl rill, comprising a drill bar, and a plurality of removable cutter b1ts arranged at the lower end'of said bar, said bitsbeing formed witha horizontal cutt ng edge at the bottom and a vertical cutting edge at theside and having enlar ed ver tically extending portions inward from isposed within corresponding recesses in a lower part of said drill bar to hold the bits n lace and the bottom cutting edges of sa1d Eits extending beyond said vertical enlarged portions and converging in matching relation at the center of the drill.

3. A rock drill, comprising a drill bar having a socket member formed with a pluralit of substantially circular recesses. extendlng longitudinally of the bottom of the socket member, the said circular recesses having extensions dis osed radially of the socket-member and ormed with parallel sides and opening on to the peripheral face of the socket member, the bottom of said edge, said transversely extending socket'member having radially extendin slots registering with the extensions of sai substantially circular members and extending from the center of said socket member to the eriphery thereof at the bottom face of said socket member, and a plurality of bits, each having a bottom portion provided with a cutting edge, a transversely extending portion provided with a side cutting ortion being of a cross-section to exactly it the substantially circular recesses and radial extensions formed in said socket member.-

4. A rock drill, comprising a drill bar having a socket member, the bottom face of the socket member being provided with radial slots converging to the center thereof, said slots, having tion of each slot having an enlargement extending transversely thereto and longitudinally of the socket member, and a bit for each slot having a cross-section corresponding to the slot' and enlargement, whereby the bit may be inserted in the bottom socket and held fromlateral displacement.

MARTIN HARDSOCG.

parallel faces and a por-- 

